Dressing fixture for contouring grinding wheels



June 16, 1953 w. MUENCH 2,642,059

. DRESSING FIXTURE FOR CONTOURING GRINDING WHEELS Filed Jan. 7, 1950 2Sheets-Sheet 1 INVENTOR" lflaZier Nuezzch June 16, 1953 w. MUENCH DRESSING FIXTURE FOR CONTOURING GRINDING WHEELS Filed Ja'n. '7, 19595 2 Sheets-Sheet 2 INVENTOR wal ie'r Muench ATTORNEYS.

BY Wm,

Fig. 1.

Patented June 16, 1953 Walter Muench', Newark, N.- .L, assignor to Walter :Muencm; Incorporated; Newark,- N; J a corpof ration of New Jersey Appl'icafion-Janiiary v, 1950,

serial N6; 137,321

14 Claims. (01. 1 25-11) This invention: ridt'es' 156' with which went, withthe aido'f dlaxfiond t atismountc in a tool-shank, concave convex radii in the circumferential partof a? wheeh I I in order to g'rinda precisionconcave or convex forming tool-bit wmea to be uSedf ih a lathe or so-c'alle'cl screw-mac inethef' g-rinding Wheelrnust be sotrinim'ed with adiamgnd tool that it imparts the shap'reduired for the wheel to-grind clearanceontheformingtool-bi-t. II

To produce that clearancecutting effect on the grinding wheel the" diafiiond tool holding fi'iitur'e must be tilted from 2" to 7' degrees, depending on the clearance require whichdiilers, when the parts to be so machined are madefrom aIuI ninum, brass bronze copper; iron, magnesium; toolsteel ofstainless steeletcL ere; I II 7 I I All fixtures new in usefwi'th double-end'bearing supports can betilted'onlyby putting a'piefc'e of fiat stock of varying" thickness" under one end of thefixtur'ei I I M I II I I By" this procedure theholdingpower of the magnetic chuck, on which is held in position, is impaired to suchan" extent that the fixture must be packed up on both sides," with magnetic parallels to prevent shifting of the fixture while in operation" under the grinding wheel. I I

However, in spite of any? reea'utions' takenwith parallels" the ins that the fixture we lifted up if inadvertently the grinding wheel should be'fed' down a trifle'too'iast toward the diamond-tool that is' cuttiml." the required contourinto the periphery of theg'ri'riding wheel.

Another disadvantage in" the oldstyle' radiusdresser is the utter impossibility to apply a sinebar to do" modern high-grade precision work'by a safe, secure and e'fiicient method.

To overco'm'ethe foregoingdeseribe'd faults is the purpose of the invention presented herein.

For a clear understandingof the many new features offered iri'this" i "venues-and to all personsversed in the art to fullyco'r'ripreheri'd the advances" made" in mechanical functions and the consequenu g'reatly e'rihahed operational fa'ci lties, drawings, depicting" a? preferred form have beenannexed in which: I p I I I Fig. l is 'a front-viev'fpfthefixture; constituting basically a so-called radius-dresser.

Fig. 2 is a-top-vie'w' of the fixture shown in Fig; 3 is a' -left inFi 1, I Fig; 4 is a fragmentary" left side-view of the fixture shown in Fig-s wlth th vertical deadsia-view urine fiiiture shown "thereon to" determine the vertical position of theswing block; parts being broken away; I i

Referringnow to the drawings iIIWhich' similar reference characters correspond'to the same part or picein all the different views shown, I is the U-shaped 'basemembr in which the swing-block or cradle 2 movable 2:18'0 degree are, being held centrally located by the ho1low', end"-fianged shaft-pieces II 3 3 precision fit graphited bronze-bearings 4: 1, which are securely placed in the upper ends of the upright arms of the In the middle f the swing block 2 a close"fit= ting'tool-saddle' 5 is movable about afulcrum-pin 6' so that the diamond holding tool 1 which is held tight in the rectangular opening) by two et-screws 49 4aian be put in an angular position. i

The' smeared served slot' il 'fland I0'-'-l0 correspondto ria sweeps taken from the fulcruni-p'in [5 and serve the purpose't'hatthe tool"- s'addle5, which carr' s" t t 4 z amtfid m s e; i its eiqYe en i e ur locked i any angular p'os'itiontothe-'swing-block 2* with thescrews lI I 'll f-llll'.

must be'form ground with a grinding-wheel bit intowhich the respective required radius 'hafsffirst been produced" by the diamond holding tool I,

positioned in ap-fec isely calculated'setting inthe Wh m q neeve e i'pei e si eral orm to'o'l bitis tobec'ut into theperiphery' of a grind- In all cases-"the preliminary vertiearseaing mg wheel with the aid of a? diamond holding: tool t form-tool plates, is the tool-saddle 5 shifted a number of degrees and then only after the vertical calculated height setting of the diamond holding tool 1 has first been carried out with the tool-saddle 5 in the horizontal zero-line position.

By shifting the tool-saddle 5 a number of degrees, the diamond tool will cut a concave or convex contour in the periphery of a grinding wheel which would be slightly deformed or at variance with relation to a true precision radius because of the slightly off-center relation of the diamond with relation to the axis of the wheel being dressed.

Now, when this grinding wheel, with the contour which is slightly irregular or deformed as aforesaid, is used to grind a tool-bit, the somewhat deformed contour in the grinding-wheel periphery will, however, grind not only the correct desired concave or convex radius on the tool-bit end, but will also grind the right clearance necessary for the tool-bit to function as a cutting-tool when used on metal parts.

However, one important requirement in this whole procedure should never be overlooked and that is that the tool-bit, when under the contour forming grinding'wheel, has to be set-up to exactly the same degree shift position as was applied for the tool-saddle slant in the radiusdressing fixture. Y

With the ever increasing demand in industry for greater output at lower costs, the exact, correct and right clearance on a tool-bit used in automatic turret lathes and screw-machines can either mean profit or loss.

The absolutely correct perfectly right clearance on a tool-bit means that it is neither too small .nor too large.

With the development of special tool-bit steels like stellite and carbide-tipped bits, the clearance cannot be expressed any longer in degrees or fractions of degrees, but in minutes and seconds of degrees, 50 that it has become imperative to use a sine-bar as the best and most reliable method for setting a radius dressing fixture to grind modern tool-bits to do super-precision work, have great endurance and show no spoilage in long run, high-speed mass production without any tool break-down whatsoever.

Tool-bits with insufficient front-clearance will drag on the work, leaving it rough, uneven and inaccurate.

Tool-bits with too much front-clearance will chatter, leaving marks on the work and cause variations in size. As the cutting-edge is frail, it will wear away too quickly so that continuous resharpening and re-setting becomes necessary.

The many basic metals and alloys in use today, have each and every one their own characteristics as regards state of hardness, ductility, etc. so that a short name: machinability is being applied to express in a single term the many, varying degreed qualities in all materials known at present.

Once the best front-clearance for a concave or convex form-cutting tool-bit has been found by experimental try and apply methods, notations should be put down on the blue-prints as a guide for the tool-maker in the shop, so that he can .set the sine-bar to the precise position on the tool-saddle 5 to duplicate a tool-bit in exactly the same minute detail as was previously found to be performing outstandingly good.

The tool-saddle 5 in this herein presented and fully described novel fixture is therefore provided with sine-bar facilities insofar as an initial or starting disc I3 is fastened with a set-screw to the revolving fulcrum stud 6 and the second, or measuring-disc I4 is secured to the stud l2 mounted on the saddle 5 in the manner illustrated in Figures 1 and 2. The centre distance between the two discs l3 and I4 gives a five inch sinebar range, or in other words the disc centers are spaced five inches apart.

The diamond I5 is fused into the holder 7 which is centrally located and held by set-screws in the very close fitting opening 8 in the tool-saddle 5. An elongated rectangular opening I8 is also provided in the middle of the horizontal bar-section of the U-base l for the purpose that the diamond holding tool I will have sufficient side clearance when the tool-saddle 5 is shifted and used in an angular position.

The diamond holding tool I is provided with a precision located pin I9, by the use of which it is possible to set the diamond-tool 'I up for convex grinding-wheel trimming insofar, as it is only necessary to slip a small size block, as for instance the one marked 20 which measures .250 inch, under the pin [9 and which then brings the very top-cutting edge of the diamond l5 one quarter inch (.250 in.) below the horizontal center-line c'd of the whole radius-dressing fixture.

The procedure now in a tool-shop to cut a M; inch (.250 in.) convex radius, as an example, would be, to bring the radius-dressing fixture which is held tight to the magnetic chuck of the surface grinder, into such a position that the top-cutting edge of the diamond i5 is in the perfect vertical and horizontal center of the grinding wheel 2|.

Presuming that the grinding wheel 2| was trued up beforehand, as it should be, and the cutting of a .250 in. convex radius is required, the Wheel periphery mustbe set exactly .250 in. above the cutting edge of the diamond l5 and in this position the reading of the micrometer dial at the hand-wheel of the surface grinder machine which is manipulated to move the grinding wheel toward or from the work should be carefully noted.

With this in mind, the surface grinder is started up and as the wheel is revolving at great speed it is fed slowly down and at the same time the swing-block 2 is continuously moved by hand degrees turn) to the right and the same distance to the left.

While this is going on, the micrometer-dial at the hand-Wheel should be closely watched and when it finally appears that the wheel 2| has been moved .250 in. towards the diamond the surface grinder is switched off and the radius contour, that was cut, is now inspected with precision gages. If the radius in the Wheel is found to be satisfactory for the job the radiusdressing fixture is taken ofi the machine table and the work piece is set up to have the radius that is in the wheel cut into it.

The position the swing-block '2 takes on when it is moved turn to the right, is indicated in Fig. 3 with short dash-lines. When it is moved turn to the left, it is indicated in Fig. 3 with clotand long dash-lines.

In order that the swing-block 2 cannot in the slightest be moved more than 90 degrees to the right and 90 degrees to the left, a precision stopplate 22--22 is fastened with flat-head screws 50-5ii-56=-5i3 and heavy dowel-pins 51-51- 51-5! on top of each upright leg of the U-base i.

When the swing-block 2 comes to the end of the 90 degree right hand turn, the surfaces 24-24 of the left and right sidefwing-shaped extensions 23-23 will come in contact with the surface 25-25 of the stop-plates 22-22 Fig.

1 and Fig. 2 See dotted lines in Figure 3.

When the swing-block "2 now comes to the end of the 90 degree left hand turn, the back of the swing-block 2 will come to rest under 'the section which overhangs from the stop-plate 22-22 at the spot marked 26 in Fig. 3 See dot and dash linesin Figure 3.

In practice it is often necessary to produce only one corner radius, for which reason it becomes imperative to have a precision stop as vertical zero-rest when the swing block 2 returns from the 90 degree right hand turn. "With the ever increasing demand for superprecision in tool-room work, naturally everything must be of high precision,-'yet practical and by all means fool-proof, even if it is only a st'opL Consequently the here'in presented vertical dead-zero stop for the described novel radius cutting fixtures should fulfill all reasonable expectations. V

One must bear in mind that the ffine grinding dust, produced in the action of cutting radii in wheels settles down and of course stays on any 'flatsurface.

The vertical dead-zerostop in the presented invention consists of hardened s'hort rail "pieces 21-21, shown in Fig. '1 and Fig. 2; These rail pieces'are radius ground so that only very'narrow ridges remain at each side of the half-round curves and which are the points of contact with the back of the swing-block 2.

The fine dust that comes off a grinding-wheel when cutting 'a radius on the periphery cannot cling to the verticalp'osition'ed narrow stop-edges of the hardened'rail pieces 21-21 which are held tight in slots provided for that purpose in the support steel-bar 28, which is accurately'putin place by dowel-pins 29-29 andse'curely fastened with filister-head screws 30-30-30-36 t'o'the U-base I as shown at the top of Figure 2.

The swing block extensions 23-23 are "provided with holes 31-31 in which'moves freely the rod 32 shown only in Fig. 2. o

The stop-collars 33-33 keep the rod 32 in'its assigned position. This also holds true withthe handle-bushing which'has-free rotary movement on the rod 32 andis being'held in the desired position by the two collars 35-35.

The end knobbed handle .36 extends approximately 4 inches from the bushing 34 so that, when in practical operation, the swing-block '2 is moved left and-right'through an arc of 180 degrees, cutting a full'half-circle radius'inagrinding wheel, the operators' hand is always 'a'safe distance from the wheel, avoiding thereby "indries which havebeen very prevalent in shops using old style radius-dressers.

In regard to the engravedjdegr'ee-lines*Dfto "1 onthe'be'veled end '55 of the tool-saddle '5', it

should be stated that they maybe'appreciated in some shops where only simple'work is done, or in 2 shops where staple :articles areY'made and where all'tool-work is standardized overthe years, relying in everything on degrees'settin'gs.

In some practice's it may be found desirable toremove the pivotally'mounted saddle and 'mount a larger diamond tool directly in the large opening ['8' in the horizontal bar-section ofthe swing block rand locked 'in"acalculated"position by two set-screws31-3'|. V

In the 'fii'rt'ure as shown in'the drawinesgthe 6 inch diameter wheelsncan beused for convex radii larger than inch. Radii larger than inch are used only for diessand punches, so that a shiftable arrangement like the previously described tool-saddle tilting is not required in this case. a Y

The end fianged hollow shaft-pieces :3-3 are pinned with precision taper-pins 38-33-38-38 to the swing block'2 in such a way that the holes through the center of shaft-pieces .3-3 remain clear and free. The holes through the center of the shaft-pieces 3-3 serve the purpose of permitting a 12 inch long, round, close fitting shaft to be pushed through :for the purpose of checking with sensitive indicators :the precision alignment relative to the base and'the two sides :ofthe fixture. .1

The irr'egular'line 39 garoundthe View inFig. 2 indicates the existence of the magnetic chuck on which the novel radius-dressing fixture in Fig. 2 is held tight and, being supported by four -magnetic parallels 40-40-40- 30, is lined up square to the ways of the machine against the back-"stop -41 which is a stationary part of the magnetic :chuck and is :set in position with .a sensitive indicator.

Thefourthreadedbottom-holes 42-42-42- 12 in the U-base I are :for :the purpose to fasten the support-platen .0, shown in Fig. 3, to the ,novel radius-dressing fixture and. thereby increasing the-hold ion the top-.surfacesof the'magnetic chuck and any texistan'c'epf any "top-heaviness of fixture as a whole isalso, at the same time, reduced to aminimum; perhaps even completely overcome.

Perfectly. in'the centre of thehorizontal bar of the U-base l a precision slide plug isrheld by the set-screw '48 .in the hole .45. .The slide-plug can "be pushed into a corresponding hole '45 in the swing-block 2 through a smaller hole 41 below hole "45. Pushing the "slide-plug upward a short distance into the hole "46 but letting the major portionlof itslengthremain in the hole 45, then by tighteningatheset-screw 48 on a fiat provided in'the slide-plug the two'main parts of the fix- Iture, :namely the u-base I and the swing-block 2 are withintheselves in-an immovable position.

This oan be most readily "utilized by inserting any kindiof a pointed diamond .tool into the rectangular opening of the tool-saddle -5 and lock the diamond-tool .in a handy position.

.Now the grinding-wheel can be quickly and easily trued up in preparation for a radiuscutting operation.

'.This'truing up, pointed diamond tool-is now removed from the tool-'saddle'fiand with the aid of a wooden driftthe slide-plug is pushed back 'into its seat in th lhole '45 in the swing block 2 and locked in itsseat bythe set-screwAB.

While I have illustrated and described myinvention with some degree of particularity, I

realize, that in'pra ctice various alterations there- Having thus -described "my invention, "what I claim as new and "desire-"to secure 'byUnite'd States Letters Patent isz 'IQIn a device of'the character described, a

'U-shape'dbase member comprising a base-portion and a pairv of support arms extending in parallel spaced relation from said'base portion and in perpendicular relation thereto, a U-shaped swing-blockcomprising a'base portion and a pair of'mounting arms exten ing, in parallel spaced relation from saidswing-block basejportion beswingably supportin the swing-block arms on the base member arms, the spacing of the swingblock arms providing a central space between said swing-block arms in which to accommodate projection of a work piece, a diamond carrier, a cutting diamond on said carrier and projecting therefrom into the space between the swingblock arms, means supporting said carrier on the swing-block base portion between its arms and in position for engaging with a work piece as the swing-block is swung on its bearing support, each said swing-block arm having stop wing means projecting laterally therefrom, each said base member arm carrying a stop projection engageable by the stop wing means as the swingblock is swung laterally in one direction and by the swing-block arms as the swing-block is swung in the opposite direction to limit the swing-block to a maximum of 180 of swing movement, and handle means extending lengthwise between the wing means at the respective ends of the swingblocl; and manually operable for imparting swinging movement to said swing-block.

2. A device as defined in claim 1 in which the handl means comprises a rod extending between and attached at its ends to the wing means at the respective ends of the cradle, and a handle rod pivoted to the rod intermediately of its ends and projecting radially therefrom.

3. In a device of the character described, a U -shaped base member comprising a base portion and a pair of'support arms extending in parallel spaced relation from said base portion and in perpendicular relation thereto, a U-shaped swingblock comprising a base portion and a pair of mounting arms extending in parallel spaced relation from said swing-block base portion between the base member arms, bearing means swingably supporting the swing-block arms on the base member arms, the spacing of the swing-block arms providing a central space between the swing-block arms in which to accommodate projection of a work piece, a diamond carrier, a cutting diamond on said carrier and projecting therefrom into the space between the swing-block arms, means adjustably supporting said carrier on the swing-block base portion between its arms for movement of adjustment in a direction perpendicularly with relation to the swing axis of the swing-block mounting and in position for engaging with a work piece as the swing-block is swung on its bearing support, the bearing supports for the swing-block arms having a common axis with which the swing-block base portion bears parallel spaced relation, and said carrier supporting means including a saddle to which the carrier is attached, pivot means mounted on the swing-block base portion adjacent one of the swing-block arms and swingably supporting the saddle on the swing-block base portion so that it can be swung relatively to the swingbioclr base por ion to vary the angle of projection of the carrier and the carried diamond with 3 saddle extends along approximately the full length of the swing-block base portion and is swingably mounted at one of its ends on said swing-block base portion, and wherein the free end of the saddle and the adjacent portion of the swing-block base portion are equipped with cooperating scale means eii'ective to determine adjustments of the saddle on its swing mounting.

6. A device as defined in claim 3 in which the saddle extends along approximately the full length of the swing-block base portion and swingably mounted at one of its ends on said swing-block base portion, and wherein there is included a cylindrical sine bar receiving disc pro jecting laterally from each end of the saddle, one said disc being disposed concentrically with relation to the swing center of the saddle.

7. A device as defined in claim 3 in vwhich the saddle extends along approximately the full length of the swing-block base portion and is swingably mounted at one of its ends on said swing-block base portion and inverted U-shaped in cross section so as to straddle the swing block base portion throughout substantially the full length thereof.

8. A device as defined in claim 3 in which the saddle has a gaging surface thereon beside the carrier, and the carrier has a gaging surface overlying the first mentioned gaging surface so that by insertion of a selected gage block between said gaging surfaces the desired degree of projection oi the diamond beyond the gaging surface of the saddle be accurately determined.

9. A device as defined in claim 3 in which the carrier is adjustably supported on the saddle so that the degree of projection of the diamond into the work piece receiving space can be varied, the sadcL, having a gaging surface thereon beside the carrier, and the carrier having a cylindrical pin projecting laterally from the carrier and providing a gaging surface overlying the first mentioned gaging surface so that by insertion of a selected gage block between said gaging surfaces the desired degree of projection of the diamond beyond the gaging surface of the saddle can be accurately determined, said carrier being rectangular in horizontal cross section and snugly fitted in a receiving recess in the saddle, and said pin projecting at opposite sides of the carrier so that the carrier is mountable with either pin end projecting in either lateral direction.

10. A device as defined in claim 3 in which the saddle and the swing-block base portion each has a recess in which to receive and support the diamond ca rier, said saddle being removable to expose the swing-block base portion recess when the same is to serve as a mounting for the diamond carrier, and means engaging the swingblock base portion directly beneath the center of the diamond being included for securing the swing-block against swinging movement on its trunnion mounting.

11. A device as defined in claim 1 in which the stop projection projects into the path of travel of the swing-block from the top of each base member arm and includes an upright portion engageable by the stop wing means and a stop surface engageable by the respective swing-block arm and which is downwardly directed so that foreign matter which. might interfere with accurate stopping of the swing-block swing movement cannot readily collect thereon.

12. A device as defined in claim 1 in which 5. A device as defined in claim 3 in which the there is also includeda member removably at- -tached to the base member tached to the base member base portion and having stop members projecting therefrom for engagement by the swing-block base portion when it is desired to limit swing movement with the diamond directed vertically, said stop members being so spaced with relation to the stop wing means engageable stop projection as to cooperate therewith in limiting the swing-block to 90 of movement.

13. A device as defined in claim 1 in which there is also included a member removably atbase portion and having stop members projecting therefrom for engagement by the swing-block base portion when it is desired to limit swing movement with the diamond directed vertically, said stop members being so spaced with relation to the stop wing means engageable stop projection as to cooperate therewith in limiting the swing block to 90 of movement, each said stop member being shaped to present sharp edge portions for stop contact with the swing-block base portion so that no foreign matter can collect on the stop members in position for interfering with accurate stop contact with said swing-block base portion.

14. In a device of the character described, a U-shaped base member comprising a base portion and a pair of support arms extending in parallel spaced relation from said base portion and in perpendicular relation thereto, a U- shaped swing-block comprising a base portion and a pair of mounting arms extending in parallel spaced relation from said swing-block base portion between the base member arms, bearing means swingably supporting the swing-block arms on the base member arms, the spacing of the swing-block arm providing a central space between said swing-block arms in which to accommodate projection of a work piece, a diamond carrier, a cutting diamond on said carrier and projecting therefrom into the space between the swing-block arms, said bearing means including WALTER MUENCH.

References Cited in the file of this patent UNITED STATES PATENTS Precision Radius Dressing, from the folder:

The Little Wonder Radius Dresser, by George Scherr Co., Inc., 128 Lafayette Street, New York, NY, 

